There is only one fuel which is even theoretically clean - fusion. Unfortunately, technology is still years away from achieving it. Who knows when the great leap will be achieved, next week, or next millenium.
Solar power suffers from the same problem. The solar panels of today are far from efficient, and converts to usable electricity but a small fraction of the sunlight that falls on it.
Hydroelectric power is very clean, but cannot be built just anywhere, and the ecologists go nuts about drowning large areas.
But there have been instances where people (or a government) put national resources behind an idea that was impossible at the time, with the knowledge that they would have to invent the technology to make it work. The Manhattan Project and the Apollo Program are two good examples. Maybe that is what is needed to make that big step to make fusion work or make solar power viable on a large scale.
The problem there is that the Manhattan Project and Apollo were both created out of a percieved life-or-death need to succeed, and merited massive and expensive efforts to achieve them with a strict timeline to meet ("before the Germans" for the Manhattan Project, and "Before this decade is out" for Apollo).
With fuel/power prices as low as they are today, there is no such percieved emergency. Hiking fuel taxes would be artificial, and will not achieve the sense of urgency. People are also selfish in their actions - people voted for, and re-elected politicians in California who imposed ridiculous targets on car manufacturers to sell non-poluting cars, but nobody bought them when they became available. Basically they said, "Cars should be clean, but make my neigbor buy it, not me."
The only way for this sense of urgency to be created if for a true shortage to come along, or some approaching calamity with a certain and near deadline.
The only thing you should feel when shooting a terrorist: Recoil.